There are various known tools and instruments for removing biological tissue samples from the body. For example, biopsy needles and punches are used when a small tissue specimen is required for examination, for example, to identify certain medical conditions. Another example of the biological tissue which is often desired to be removed or harvested is a hair follicle.
Hair transplantation procedures are well-known, and typically involve harvesting donor hair grafts from the “donor areas,” for example, side and back fringe areas of the patient's scalp, or other body surfaces, and implanting them in a bald area (“recipient area”). Various techniques were developed over the years for harvesting donor hair grafts. Recently more physicians employ a technique called Follicular Unit Extraction (“FUE”) that allows harvest of individual follicular units without a need to cut a strip of tissue from the patient's scalp.
An FUE method for harvesting follicular units utilizes a hollow needle punch having a cutting edge and an interior lumen with a diameter of for example, 1 mm. Generally, based on visualization of each follicular unit through magnifying optics, the needle punch advances along an axis of a follicular unit to be extracted. Thereafter, the follicular units are easily removed, e.g., using forceps, for subsequent implantation into a recipient site with a specially devised insertion needle. While it is a laborious procedure, it has distinct advantages over another known “strip harvesting” technique, like avoiding scarring associated with cutting a strip of scalp, reducing patient's discomfort, and reducing recovery time.
One of the limitations, however, of the FUE-based devices and methods is caused by the fact that the hair follicles do not maintain the same direction of growth under the skin as they do above the skin. Quite often a hair follicle significantly changes its direction or angle underneath the skin, and advancing the punch based on the visible portion of the hair follicle above the skin may result in follicle transection, damaging it or rendering it unusable for transplantation.
In general, attempts have been made to look at subsurface skin images up to about 1 mm when examining an epidermis layer of skin (e.g., for treating skin cancer). There are several publications that describe systems that have been used to allow for detection depth of up to 1.5 mm with some limited resolution to investigate at least approximate architecture of the skin lesions. Similarly, some work has been described for subsurface imaging at depths substantially greater than 5-6 mm, or to enhance the visibility of high-contrast blood vessels. U.S. Pat. No. 7,239,909 describes an imaging system to enhance visibility of subcutaneous blood vessels based on reflected infrared light. While certain developments were made to visualize high-contrast blood vessels which are usually located at least 5 mm or more below the skin level, there are no known systems or devices that provide clear images of low-contrast tissue/structures, for example, a hair shaft below the skin, and/or in some instances at least a portion of a bulb of a hair follicle below the skin.
Despite certain advances in improving the tools and systems for harvesting of biological tissue, such as hair follicles, there remains a need for a more efficient harvesting tool or system that increases the yield of usable harvested specimens by visualizing the subcutaneous structure and orientation of such specimens.